import java.util.*;
public class Average5{
    public static void main(String[] args){
        try{
            Scanner console=new Scanner(System.in);
            double sum=0;
            int count=0;
            while(true){
                int number=console.nextInt();
                if(number==0){
                    break;
                }
                sum+=number;
                count++;
            }
            System.out.printf("平均%.2f%n",sum/count);
        }catch(InputMismatchException ex){
            System.out.println("必须输入整数");
        }
    }
}